Fertilization is the combining of male and female sex cells. When a pollen grain touches the top of the pistil, called the stigma, it forms a tube through which male sex cells travel downward into the ovary. An egg is fertilized inside the ovary.
In the process of photosynthesis, plants take in carbon dioxide and water and using light from the sun, they produce sugar and oxygen.
The amniotic egg is watertight, and consists of several layers of membranes. Among other structures it contains a food source for the developing embryo in the form of a yolk.
Amphibians possess a three-chambered heart that pumps blood throughout the body via a network of blood vessels.
Nerve impulses occur when the electrical charge across a neuron cell membrane reverses. Nerve impulse is also referred to as "action potential" and involves the reversal and restoring of charges across a neuron cell membrane.
Neurons are one kind of nerve cell that transmit signals throughout the body.
The brain has three main parts-- the brain stem, the cerebellum, and the cerebrum. Let's start with the brain stem. It consists of the midbrain, pons, and medulla oblongata. Located just above the brainstem are the thalamus and hypothalamus.
When you respond involuntarily to a hot object, a reflex arc begins when sensory neurons in your hand detect pain. Sensory neurons then carry information in the form of a nerve impulse to the spinal cord.
The backbone encases the spinal cord, a bundle of nerves that play a key role in the central nervous system.
Nerve impulses move across spaces called "synapses" via specific chemical messengers referred to as "neurotransmitters." Special structures located on the ends of axons release neurotransmitters into the synapse when an impulse is received.
The food pyramid depicts the five major food groups: grains, fruit, vegetables, milk, meat and beans.
Oxygen mixes with blood in the lungs and is then pumped throughout the body.
A ball and socket joint is made of a bone with a rounded end that fits inside a cup-like pocket of another bone, enabling bones to move in a circle. Hip joints and shoulder joints are examples.
The splitting of a parent cell into two new cells is called cell division.
Chloroplasts are the places in plant cells where photosynthesis occurs. Chloroplasts contain chlorophyll.
Food and water move through the cell membrane into the animal cell, while waste products cross the cell membrane to exit the cell.
Capillaries are the smallest blood vessels.
The heart is responsible for circulating blood throughout your body.
There are eight main taxonomic levels in the modern taxonomic hierarchy.
Going from the broad to the specific, the house fly is in the domain Eukarya, the kingdom Animalia, the phylum Arthropoda, the class Insecta, the order Diptera, the family Muscidae, genus Musca, and species domestica.